Noise reduction is widely used in audio processing systems to suppress or cancel unwanted noise in audio signals used to transmit speech. However, after the noise cancellation and/or suppression, speech that is intertwined with noise tends to be overly attenuated or eliminated altogether in noise reduction systems.
There are models of the brain that explain how sounds are restored using an internal representation that perceptually replaces the input via a feedback mechanism. One exemplary model called a convergence-divergence zone (CDZ) model of the brain has been described in neuroscience and, among other things, attempts to explain the spectral completion and phonemic restoration phenomena found in human speech perception.